Method and apparatus for filling open containers with a powdery product

ABSTRACT

Apparatus and method for filling a container ( 7 ), particularly an open bag, with a powdery product has the following features” a net scale ( 1 ) situated above a tube arrangement and/or hopper arrangement ( 2 ), which terminates in a filler neck ( 6 ) above the container ( 7 ) to be filled while preferably projecting into this container. An intermediate chamber ( 3 ) is arranged downstream of the net scale and upstream of the container ( 7 ) to temporarily hold at least a portion of the product released by the net scale, and a compacting device ( 8, 9 ) is provided for compacting the product placed inside the container ( 7 ).

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a divisional of prior filed copending U.S.application Ser. No. 11/568,833, filed Nov. 8, 2006, the priority ofwhich is hereby claimed under 35 U.S.C.§120 and which is the NationalStage of International Application No. PCT/EP2005/004930, filed May 6,2005, which designated the United States and has been published asInternational Publication No. WO 2005/110849 and which claims thepriorities of German Patent Applications, Serial No. 10 2004 024 476.6,filed May 14, 2004, and Serial No. 10 2004 037 107.5, filed Jul. 30,2004, pursuant to 35 U.S.C. 119(a)-(d).

The contents of U.S. application Ser. No. 11/568,833, InternationalApplication No. PCT/EP2005/004930, German Patent Applications, SerialNos. 10 2004 024 476.6, and 10 2004 037 107.5, are incorporated hereinby reference in their entireties as if fully set forth herein.

BACKGROUND OF THE INVENTION

The invention relates to an apparatus and a method for filling an opencontainer, preferably an open bag

In order to accurately weigh a product, it is common to split theproduct flow into a coarse stream and a fine stream. A worm may herebybe used for example as dosing member. This type of product feed isprovided exclusively for realizing a high weight accuracy.

The net system involves in some cases a separation of the product flowinto fine and coarse streams when being filled into the scale, whereasthe gross system involves a separation during filling the container.

In general, the gross system provides only little productivity which isdisadvantageous. At the same time, there is no possibility to compactthe product during the weighing phase because any type of manipulationhas an impact on a weight.

Gross systems are also known which provide an intermediate compaction ata non-critical weighing moment during the weighing and fillingprocesses.

Cited as prior art are U.S. Pat. No. 3,209,844 A, DE 36 40 520 A1, U.S.Pat. No. 3,404,742 A, CH 683 251 A5, DE 38 11 880 A1, U.S. Pat. No.3,589,411 A, GB1 011 653 A, DE 101 32 715 C1, CH 611 216 A5, U.S. Pat.No. 4,275,775A, and GB 661 224 A.

U.S. Pat. No. 3,209,844 describes a filling device with a scale by whicha coarse weight is pre-metered (underweight) which is then fully emptiedinto the filling container. Subsequently, a volume dosing wheel suppliesa fine stream.

DE 36 40 520 describes a filling device to first weigh the quantity tobe filled and then to discharge it directly into a bag.

U.S. Pat. No. 3,404,742 describes a weighing device by which a coarsestream of the filling material is volumetrically pre-metered andreleased in a scale receiver. Doses of the fine stream are then added.Subsequently, the total filling material portion is dispensed.

CH 683 251 A5 uses a differential scale as weighing device and dispensesthe released product directly from the scale as coarse and fine streams.

DE 38 11 880 A1 deals with the problem of maintaining the fillingmaterial continuously under vacuum during an otherwise known fillingprocedure in order to prevent contamination as a result of environmentalimpacts.

U.S. Pat. No. 3,589,411 describes a filling apparatus having twoseparate connections into a bag to be filled. Each of the connectionshas its own weighing mechanism for alternatingly weighing the material.A feeder with an impeller that rotates at constant revolution compactsthe product so that the material to be filled drops pre-compacted inaccordance with the revolving compartments into a filling container. Theimpeller thus assumes the function of ventilation and compaction of thefilling material. (Continuous transport as a result of productcompaction).

All afore-mentioned apparatuses lack basically apparatuses for productcompaction or are dimensioned for only little output.

Powdery products which are also very fine have the characteristic ofintake of air during transport and also during the filling operation,leading to a significant increase in volume. As a consequence, the bagsnormally used for packaging must have a respectively great volume toprovide enough space for the product in the bags.

After the product has again released the air entirely or partlyfollowing the filling of the bags, for example through introducingcompaction measures or after elapse of a certain time, the product takesup a respectively smaller volume, so that the bag or the bag articlebecomes too big, i.e. packaging material is given away, resulting inhigher costs and problems when stacking the bags. The afore-mentionedprior art is unsuitable to overcome these problems satisfactorily.

SUMMARY OF THE INVENTION

The invention is thus based on the object to provide a method andapparatus for filling containers with a powdery product, by which theafore-described problem is overcome in a simple manner.

According to one aspect of the invention, an apparatus for filling anopen-topped container, preferably an open bag, with a powdery product,includes a net scale above a tube arrangement and/or hopper arrangement,which terminates in a filling neck arranged above the container to befilled and preferably projects into the container, an intermediatechamber disposed downstream of the net scale and upstream of thecontainer for temporarily holding at least a portion of the productreleased from the net scale, and a compaction device for compacting theproduct filled into the container.

With respect to the method, a weighed quantity—i.e. net process—of theproduct is emptied from the net scale via the tube arrangement and/orhopper arrangement into the container, with part of the producttemporarily received in an intermediate chamber before being transferredinto the container.

As the invention utilizes the net weighing principle which is known perse and involves an initial weighing of the total filling materialportion before being filled, a high output can initially be realizedbecause the next portion can be weighed during the actual filling andcompaction operation.

As the total volume flow is not immediately transferred into thecontainer, the container is not overfilled despite the application ofthe net principle. This type of after-dosing following the weighingprocess with a net system is known from the prior art. Thereafter,after-dosing takes place, preferably accompanied by a compaction of theproduct in the container or bag. The bag can thus be sized fairly small.

Particular advantages of this procedure are:

-   -   1. A high productivity of the apparatus because the net scale is        able to empty the product in one working step;    -   2. A high compaction speed because the first product shot can be        quickly introduced and a max. filling degree of the bag is        ensured so that the compaction success is optimal;    -   3. A proportional addition of the product as a result of the        compaction effect in the absence of overfilling of the        container.

The remaining product flows suitably past the intermediate chamber andis transferred directly into the container, with the ratio of the splitbetween the intermediate chamber and the remaining product directlyintroduced into the container being so selected as to sufficiently fillthe bag without encountering overfilling of the bag.

Preferably, the product introduced into the container is compacted bymeans of a compaction device and the remaining product is after-dosedfrom the intermediate chamber during the initiated compaction process bymeans of the compaction device and the accompanying reduction in volume.

The method according to the invention is suitable in particular also forthe application of a rotating filling machine where the upstream netscales are arranged stationarily. In particular when such a constructionis involved, the step-by-step feed of material would be possible at allonly by increasing the complexity of the technical implementation andaccepting a high power loss.

Powdery product enriched with air has extremely high flow capability andits flow behavior can indeed be compared with that of water. In otherwords, the bag has to be very well sealed to the neck to prevent productfrom escaping to the outside and causing contamination of the bags andthe installation.

These sealing measures although also being a component of the machineare subject to wear. Furthermore, the quality of the seal is alsodependent on the composition of the bag material (folding).

As in accordance with the invention the fill level is always below thedanger zone, the afore-described problems are no longer an issue. As aresult, the operation of the apparatus is safe.

Advantageously, channels are arranged in the filling neck for carryingaway displaced air and thus preventing excess pressure in the bag. Thisfunction is no longer possible, when the fill level rises to a heightthat causes these channels to close. At the same time, there is the riskthat the product settles in these channels and escapes after removingthe bag and causing contamination of the installation and the bags.

A further important aspect during filling of bags is the demand for highcleanliness of the later closure zone of the bag. This becomes even moreimportant when the closure is realized through welding that requireshigh cleanliness of the foil inner side. The afore-described method hasproven its effectiveness especially when it comes to solving thisproblem while still achieving high filling speeds.

According to a variation, in which the intermediate chamber isconstructed over the entire hopper cross section and thus able to holdthe entire material amount, the dosing member initially is set for ahigh mass flow.

Especially preferred is a control or regulation of the mass flow by thedosing member in such a manner as to prevent a bridge formation of theneck as a result of material backup.

According to a further improvement, the dosing member controls orregulates the passing mass flow after the rapid filling action in such amanner as to prevent overfilling of the container during compaction ofthe material in the container.

BRIEF DESCRIPTION OF THE DRAWING

Preferred exemplified embodiments of the invention will now be describedin more detail with reference to the drawing, in which:

FIGS. 1 a, b show a schematic illustration of a first apparatusaccording to the invention for filling a container in two successivesteps during filling of the container by means of after-dosing with arotary feeder;

FIGS. 2 a, b show a schematic illustration of a further apparatus forfilling a container in two successive steps after and during filling ofthe container by means of after-dosing with a random dosing member, herea gate;

FIG. 3 shows a schematic illustration of a further apparatus for fillinga container in two successive steps during filling of the container,with an intermediate chamber holding the total filling content, and adosing member with the option of filling the container with controllablecoarse stream and fine stream; and

FIG. 4 shows a schematic illustration of the apparatus of FIG. 2,depicting the adiustability of a boundary wall to adjust a volume of theintermediate chamber.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIGS. 1 a, b show an apparatus for filling a container 7—an openbag—with a net scale 1, which is arranged above a tube arrangementand/or hopper arrangement 2 which terminates in a neck 6 from which acontainer 7-—especially an open bag—is suspended.

The so-called net principle is used as weighing process, i.e. the netscale 1 weighs the product being filled portion-by-portion—e.g. inamounts of 25 kg—and then releases the thus weighed portions via thetube/hopper arrangement 2 and the neck 6 into the container 7. Thisoperation provides the benefit of a particularly high productivity incomparison to the gross system.

In order to avoid hereby the detrimental effect of overfilling thecontainer 7, the product stream or at least part thereof is transferredinto an intermediate chamber 3 which is arranged in the tube arrangementand/or hopper arrangement 2. This intermediate chamber 3 receives(depending on the air content of the product) a portion of the productreleased by the net scale—preferably about 20-50%, in particular about ⅓of the product.

The remaining product flows past the intermediate chamber 3, which doesnot cover the entire cross section of the tube/hopper arrangement 2, andis directly introduced into the container 7. The ratio of the split ofthe product between the intermediate chamber 3 and the portion directlyintroduced into the container is hereby selected such that nooverfilling of the bag can be experienced (FIG. 1 a, FIG. 2 a).

Projecting into the container 7 is e.g. a compaction device 8 from itsopen-topped side, or a differently arranged compaction device 9, whichis constructed to so compact the product introduced into the container 7as to liberate a portion of the absorbed air.

During the now commencing compaction operation by means of thecompaction device 8/9 and the accompanying reduction in volume of theproduct, the remaining material is dosed from the intermediate chamber 3in such a manner that the compaction speed and the volume flow withwhich the container can be filled, correspond. As a result, maximumcompaction speed is ensured, without encountering overfilling (FIGS. 1b, 2 b).

The compaction device can be implemented in any manner suitable, forexample as a type of probe (reference sign 8, causing vibrations forexample, or a vacuum lance etc.) and/or with the aid of a shakingarrangement, e.g. with the aid of a vibrating table (cf. 9) upon whichthe container is placed.

The intermediate chamber 3 may be made of individual segments, i.e. ofseveral sub-chambers which are emptied in succession. The use of arotary feeder as dosing device 4 has been proven as most beneficialversion, with the chambers being continuously emptied via theimpeller-like rotary feeder (FIGS. 1 a, 1 b). Rotation speed and thusmetering speed can hereby be suited to the process. As an alternative,the dosing member may also be constructed in a different way (FIG. 2,showing the dosing member constructed in the form of a gate).

As the air content of the product to be filled oftentimes changes as aresult of different settling times, the intermediate chamber can beconfigured in such a manner that its volume and/or impeller can bevariably adjusted. This can be realized, e.g., by an adjustable lateralboundary wall 5 on the intermediate chamber 3, as indicated in FIG. 4 bydashed line, with the boundary wall 5 being swingably connected to thegate 4 via a hinge 12.

As an alternative to the apparatus FIGS. 1 a, b and FIGS. 2 a, b, it isalso possible to construct the intermediate chamber 3 according to FIG.3. In this arrangement, the intermediate chamber 3 extends across theentire hopper cross section of the tube/hopper arrangement 2 and thusholds the total filling amount of the material dropped from the netscale 1. Arranged at the lower end thereof is a dosing device 4 which isconstructed advantageously as rotary feeder but may also be a differentdosing device of known type.

The material dropped into the thus configured intermediate chamber maypass the dosing member 4 as coarse stream, when the filling processbegins. The dosing member has hereby the advantageous characteristic toso limit the stream as to positively prevent bridge formation and adelay in material transfer into the container 7, as a result e.g. of aclosed filling neck due to internal material friction. After thebeginning rapid filling action, the dosing member 4 adjusts downwardsthe volume stream in dependence on the fill level in the container 7 inaccordance with the parallel compaction process by means of thecompaction device 8, 9 in the bag so that the container 7 cannot beoverfilled during the filling operation.

A further advantage of the method resides in the fact that the dosingmember 4 may be blocked for a moment—at the start of the fillingprocess—to effect a temporary decoupling of the material drop so that analready attached container onto the neck can be sealed. Further, thismethod does not require a volumetric adjustment of the intermediatechamber 3 by means of e.g. an adjustable sidewall, because there is noneed for the intermediate chamber to hold a defined portion of thedropped material but in general receives the entire material beingdropped and the intermediate chamber 3 becomes insensitive againstfluctuation in apparent density and thus volume.

As oftentimes the compaction characteristic of the product changes, itis furthermore possible to equip the installation preferably with theadvantageous sensor 10 which detects the fill level of the product belowthe neck outlet 11. With this technique, it becomes possible to controlthe dosing device such that no overfilling can occur. Otherwise,provision of a safety distance would have been necessary between theproduct level and the neck outlet 11 which would result in a decrease ofthe compaction speed.

A further important fact is the transfer of the filled container 7 to asealed stage. In order to ensure a secure closure of the container 7, acertain free space must exist above the product level to enable areasonable engagement of the tools for sealing the bag. Also in thiscase, the afore-described sensor 10 provides benefits because of itsability to control the compaction process so that the presence of therequired free space is ensured.

In summary, the fore-described solution ensures high productivity of theinstallation, compact bag dimension, high cleanliness of the bags andthe installation, high security of the bag closure, and high weightaccuracy.

Separation of weighing and intermediate storage provides the advantageof a simple construction of the scale as well as an increase inproductivity because the next weighing process may take place during thefilling operation.

Especially advantageous is the application of the installation forrotating filling machines.

1. An apparatus for filling an open-topped container with a powderyproduct, comprising: a net scale for releasing a product; a tubearrangement and/or hopper arrangement disposed below the net scale andterminating in a filling neck arranged above a container to be filled;an intermediate chamber disposed downstream of the net scale andupstream of the container and configured for temporarily holding atleast a first portion of the product released by the net scale while asecond portion of the product bypasses the intermediate chamber; and acompaction device for compacting the product filled into the container.2. The apparatus of claim 1, wherein the filling neck projects into thecontainer.
 3. The apparatus of claim 1, wherein the intermediate chamberis arranged in the tube arrangement and/or hopper arrangement andextends across part of a cross section of the tube arrangement and/orhopper arrangement so that the first portion of the product isintroduced via the intermediate chamber into the container while thesecond portion of the product released by the net scale is introduceddirectly into the container.
 4. The apparatus of claim 1, wherein thefirst portion of the product amounts to about 20-50% of the product. 5.The apparatus of claim 1, wherein the first portion of the productamounts to about ⅓ of the product.
 6. The apparatus of claim 1, furthercomprising a fill level sensor for detecting a fill level in thecontainer.
 7. The apparatus of claim 1, wherein the intermediate chamberis comprised of several sub-chambers which can be emptied separately. 8.The apparatus of claim 1, further comprising a dosing member provided inthe intermediate chamber for metered release of the first portion of theproduct into the container.
 9. The apparatus of claim 8, wherein thedosing member is a rotary feeder.
 10. The apparatus of claim 8, whereinthe dosing member is a controllable swivel gate.
 11. The apparatus ofclaim 1, wherein the intermediate chamber has a variable volume.
 12. Theapparatus of claim 1, wherein the compaction device includes a probeprojecting into the container.
 13. The apparatus of claim 1, wherein thecompaction device includes a shaking unit.
 14. The apparatus of claim 1,wherein the compaction device includes a vibrating table upon which thecontainer is placed.